1. Field of the Invention
The present invention relates to perpendicular magnetic recording heads for performing recording by applying a magnetic field perpendicularly to a surface of a recording medium such as a disc, and more particularly, relates to a perpendicular magnetic recording head capable of recording magnetic data on a recording medium with narrow track pitches and a method for manufacturing the same.
2. Description of the Related Art
A magnetic head shown in FIG. 13 is a recording magnetic head used for a perpendicular magnetic recording device. The perpendicular magnetic recording device in which a recording medium is magnetized in a direction perpendicular to the surface thereof is able to record magnetic data at a high density as compare to a device in which a recording medium is magnetized in a direction parallel to the surface thereof.
FIG. 13 is a cross-sectional view of the structure of a magnetic head used for a perpendicular magnetic recording device, and FIG. 14 is a front view of the magnetic head shown in FIG. 13. FIG. 13 is a cross-sectional view of the magnetic head taken on the chain line XIII-XIII shown in FIG. 14, the head being viewed along the direction indicated by the arrows.
A magnetic head H is provided at an end surface of a slider at a trailing side, the slider moving above a recording medium while floating or sliding thereon.
The magnetic head H has a main magnetic pole layer 1 and a return path layer (auxiliary magnetic pole layer) 2 provided thereabove. The main magnetic pole layer 1 and the return path layer 2 are formed of a ferromagnetic material.
An end surface 1a of the main magnetic pole layer 1 and an end surface 2a of the return path layer 2 are disposed with a predetermined distance provided therebetween. In addition, the return path layer 2 and the main magnetic pole layer 1 are magnetically coupled to each other at a magnetic coupling portion 1b. 
Between the return path layer 2 and the main magnetic pole layer 1, a non-magnetic insulating layer 3 is provided which is made of an inorganic material such as Al2O3 or SiO2, and inside the non-magnetic insulating layer 3, a coil layer 4 made of a conductive material such as Cu is formed.
The area of the end surface 1a of the main magnetic pole layer 1 is considerably small as compared to that of the end surface 2a of the return path layer 2.
Accordingly, a magnetic flux φ is concentrated on the end surface 1a of the main magnetic pole layer 1, and in a portion of a hard film Ma of a recording medium M, which faces the end surface 1a, a magnetic datum is recorded by the magnetic flux φ. The recording medium M is, for example, a disc-shaped medium and is formed of the hard film Ma which is provided at the magnetic head side and has a high residual magnetization and a soft film Mb which is provided behind the hard film Ma and has a high magnetic permeability. The magnetic flux φ generated from the main magnetic pole layer 1 enters the return path layer 2 through the soft film Mb.
The return path 2 of a perpendicular magnetic recording head, shown in FIGS. 13 and 14, is formed to have a convex portion 2b protruding toward the main magnetic pole layer 1 side. When this convex portion 2b is provided, the spread of a magnetic flux passing from the main magnetic pole layer 1 to the return path layer 2 through the recording medium M can be suppressed, and hence the edge of a recording track on the recording medium M can be clearly defined, and a higher recording density can be achieved by narrowing a track. A perpendicular magnetic recording head as described above has been disclosed in Japanese Unexamined Patent Application Publication No. 2002-92820.
In addition, in Japanese Unexamined Patent Application Publication No. 2002-133610, a perpendicular magnetic recording head as shown in FIG. 15 has been disclosed in which a facing surface 10a of a main magnetic pole layer 10 has a taper portion 10c. 
When the perpendicular magnetic recording head is moved between an outer periphery and an inner periphery of the disc-shaped recording medium M, the main magnetic pole layer 10 is inclined with respect to the tangential direction (A direction in the figure) of rotation of the recording medium M to produce a skew angle (yaw angle).
In the perpendicular magnetic recording head having the main magnetic pole layer 10 provided with the taper portion 10C, as shown in FIG. 15, the intensity of a magnetic field generated from the main magnetic pole layer 10 is high, and in addition, magnetic flux in the tangential direction (A direction in the figure) of the recording medium M converges; hence, when the skew angle is generated, the spread of the recording track width can be reduced.
The perpendicular magnetic recording head shown in FIGS. 13 to 15 is formed to enhance the magnetic field passing from the main magnetic pole layer to the return path layer 2 through the recording medium M.
However, when the intensity of the magnetic field is simply enhanced as described above, the spread of the magnetic flux passing from the main magnetic pole layer to the return path layer 2 through the recording medium M cannot be effectively reduced. In particular, when the intensity of the magnetic field is simply enhanced, the magnetic field generated from the main magnetic pole layer is spread in the track width direction (X direction in the figure), and a problem may arise in that a substantial recording track width is liable to increase.